"I've caught my foot under the rock!"
Dave immediately hastened forward, and saw that his chum was indeed fast.
The foot was wedged in a crevice, and could not be budged until Dave rolled the rock away by main force.
Then Bob grated his teeth and gave a deep groan.
"My ankle! It must be broken! Oh, Dave!"
And with another moan he fell back in a faint.
If Dave had been alarmed before, he was doubly so now, and he scarcely knew what to do. He remembered passing a pool of water a distance back, and he ran to this, filling the water bottle Bob had been carrying.
The water revived the young engineer somewhat, and in the meantime Dave cut loose his shoe. He found the injured ankle much discolored, and swelling rapidly. He bathed it, and this gave some relief, until the pain gave way to a stiff numbness.
"Now I am in a pickle," groaned Bob. "Did ever anybody run up against such luck before?"
"Better not try to stand yet," replied Dave.